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Hi,

I'm completing a new PCB for my WDC65C265 chips, with all the right ports exposed, etc. I finished my sheets and put (most of) the components on the board. However, I have no idea how to (properly) run traces, vias, copper, etc., because I've never done a PCB before. I can't afford screw this up; it is based on a design I hand-soldered on veroboard, but I've hit the performance limit with that (and other obvious problems).

Can anyone help? I'm happy to send one WDC65C265 (PLCC for this board) to someone who helps.

Jon

PS I am using LCSC components, where possible, because I want JLCPCB to put most of the non-WDC components on the board for me. Again, I've never done this before, either. For WDC parts, I selected IC sockets so I can just put them in myself.

Thanks!!!

PCB layout, like so many other things, can be a bit daunting to start into. Don't be discouraged if (when) your first PCB doesn't come out right. Fortunately, the prices for custom boards have come down so much that Rev. A (and B, and...) won't break the bank.


The 6502 primer has applicable chapters, especially 13., What About Custom PC Boards?

Cool. But, if anyone wants to help, I can give incentives

What EDA software are you using? I typically use EAGLE and its autorouter. It draws some totally bonkers traces sometimes but I can usually spot them quickly and correct manually.

I have been pretty curious about the WDC65C265. If yours is an EAGLE project I could see having time to help out.

If it's KiCAD, well, I'm trying to learn that too but I haven't actually made any designs in it yet.

EasyEDA - it is supposedly the most simple. Allegedly.

Can you share your schematic? We will happily check your circuit

What format?

I would like it in PDF. I read the PIB may be for Apple2x expansion bus so I'm curios to see how that works.
Bill

Okay, PDf:

Doing the traces for the PLCC and the RAM chips is impossible! I just can’t get it down!

I'm not sure what you're referring to; but you can definitely run a trace between their pads if you need to.

Does it pay to do a four layer board?

You most likely always want to do four-layer boards for this type of project. On the top and bottom layers go your signal and 5V traces. In the inner layers, you put a ground plane. This is to help with signal integrity.

If you haven't done PCB layout and routing before, I recommend Phil's Lab videos, for example, this is a pretty detailed course (3h) https://www.youtube.com/watch?v=C7-8nUU6e3E

You are kidding... Not that I have anything against 4-layer boards, but I can't see any reason for 4 layers with classic microprocessors and even contemporary microcontrollers. 2 layers are more than enough if you don't use BGA packages. I do PCB designs for like 25 years, using Eagle and now KiCAD (once it became usable with 6.x version) and have yet to see the necessity of 4-layers. Ok, I don't do anything above 120 MHz; with high frequencies 4 layers would be useful, but few times I did 2 MHz 24-bit ADCs with analog front end and digital back end in 2 layers and it worked better than the earlier 4-layer implementations of the circuits made by some professionals.
These, for example, were done with 2 layers:
https://hackaday.io/project/163755-sdc68k
https://hackaday.io/project/163757-sdc85

I didn't say it couldn't be done in 2 layers, especially if you know what you're doing.

But with the price of 4 layer board manufacturing being virtually identical to 2 layers now (JLC 10x10cm: 2 layers is $0.40/pcb, 4 layers is $1.60/pcb), I don't see a reason for a beginner not to make the jump. My understanding of it is, it is more about the rise and fall times of your signals than the frequency of your clock. The 65C816 for example has fast edges, it is not a stretch to think the 65C265 does also. If you use 74AC gates, they also are quite fast. Proper ground distribution starts to become important. For a beginner, it is easier to place a ground plane and not worry about it than to route ground manually. I honestly can't think of a reason to use 2 layers today, except if you're etching them at home.